I think you simply should make a break for a while. I can't say 100% sure, but Google is quite smart when determining whether a query must be blocked or not. For example, if you first send 10,000 queries within 10 minutes, then turn on the safe mode and try to send another 10,000 - it won't let you no matter how slow it goes. It kind of remembers what you were doing in the past and blocks you way before your queries become a real problem. Again, I can't tell the exact amounts you can check safely nor can I tell the exact time periods etc. But this is due to overload of queries per time.

Try to wait a bit, so that Google "forgets" you, then try with one of the safe modes.

Also note, that Google counts all queries from your IP, so if you're using some other software or tools that send queries to Google this also may affect this issue.